Network topologies and routing in the enterprise, data center, and campus networks reflect the needs of organizations in terms of performance, scale, security, and availability. For scale and security reasons, networks are often composed of multiple small domains, each serving one or more logical functions of the organization. Hosts within a domain can freely communicate with one another but traffic between hosts in different domains is subjected to additional services that help in scaling and securing the end applications.
Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.